Bra Measurements Explained

The measurements

Underbust

The distance around your ribcage directly beneath your breasts. It determines your band size. Also called the ribcage or underband measurement. See how to measure your underbust.

Snug, loose and tight underbust

Three versions of the same measurement taken at different tape tensions. Snug is the one used for sizing. The other two show how much your ribcage compresses, which helps when you are between bands.

Bust

The distance around your body at the fullest part of your breasts. Together with the band, it determines your cup. Sometimes called the overbust or full bust measurement. See how to measure your bust.

Standing, leaning and lying bust

The bust measured upright, bent forward at 90 degrees, and lying on your back. Soft tissue reads differently in each position, and comparing them gives a truer figure than the standing one alone.

The difference

Bust minus band. Each inch is one cup size. A 5-inch difference is a DD.

The parts of a size

Band size

The number in a bra size: 32, 34, 36. In UK sizing it is in inches and comes in even numbers. See what band size am I?

Cup size

The letter in a bra size. It describes the difference between bust and band, so it only has meaning alongside the band. The UK order is in UK cup sizes in order.

Cup volume

The actual capacity of a cup. The same letter has more volume on a bigger band, and different sizes can share a volume.

Sister sizes

Sizes with the same cup volume on different bands, such as 32D, 34C and 36B. See what sister sizes are.

Starting size

The size a calculator or tape measure suggests. It is the first size to try on, to be confirmed by how the bra fits.

The parts of a bra

Band (or underband)

The part that goes around your body. It provides most of the support.

Wings

The sections of the band between the cups and the back fastening.

Hooks and eyes

The back fastening. Most bras have three positions. A new bra should fit on the loosest.

Cups

The parts that hold the breasts. They may be moulded from one piece of foam, or sewn from two or more fabric panels, which is called a seamed cup.

Underwire

The curved wire under each cup. It should follow the crease beneath the breast and rest on the ribcage all the way round.

Gore (or centre front)

The panel between the cups. In a wired bra it should sit flat against the breastbone, which fitters call tacking.

Apex

The point where the strap joins the cup.

Shape terms

Projected and shallow

Projected breasts stand further forward from the chest for their volume. Shallow breasts are spread over a wider area and stand out less. The two need differently shaped cups in the same size.

Full on top, full on bottom

Where most of the tissue sits relative to the nipple. It affects whether the upper edge of a cup gapes or cuts in.

Root

The outline where the breast joins the chest. Its width and height decide which wire shape will fit.

Wide set and close set

How much space there is between the breasts at the centre. It decides how wide and tall a gore you can wear.

Fit terms

Scoop and swoop

Bringing all the breast tissue forward into the cup after fastening the bra. See the scoop and swoop method.

Quadboob

The bulge over the top of a cup that is too small.

Gaping

Empty space between the cup and the breast, usually at the top edge.

Riding up

A band that sits higher at the back than at the front, which means it is too big.

How these all fit together on the body is covered in how a bra should fit.

Frequently asked questions

What two measurements do I need for a bra size?

Your underbust, taken snugly around the ribcage beneath the breasts, and your bust, taken around the fullest part. The first gives the band and the difference between the two gives the cup.

What does the number in a bra size mean?

In UK sizing it is the band size in inches, which corresponds closely to your underbust measurement rounded to an even number. It is not your bust measurement.